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Hint : NO_EXPAND

原创 Linux操作系统 作者:tsinglee 时间:2007-11-28 13:58:02 0 删除 编辑

The NO_EXPAND hint prevents the cost-based optimizer from considering OR-expansion for
queries having OR conditions or INLISTS in the WHERE clause. Normally, the optimizer would
consider using OR expansion and use this method if it decides the cost is lower than not
using it.

SELECT /*+ NO_EXPAND */ name, salary
FROM emp
WHERE cost_center=9
OR cost_center=10;

[@more@]

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